Antibody-based therapies have come to the forefront in recent years as effective treatment options for numerous diseases such as cancer or autoimmune diseases, in conjunction with many new developments in antibody engineering and production technologies.
One of the major challenges associated with antibody formulation and delivery is maintaining the stability and form of the antibody therapeutic, in particular for long-term storage and for transport. Antibodies, like other types of protein-based therapeutics, are susceptible to physical and chemical instability under stress conditions such as temperature changes from freeze-thawing or during transport, exposure to light, oxygen or chemical/solvents, shear stress, and pH stress.
They may undergo denaturation (e.g. loss of tertiary and/or secondary structure) or interact to form aggregates. While antibody aggregation can occur in both the liquid and solid state, it is especially problematic in liquid formulations, especially at high concentrations of antibody. Antibodies are typically therapeutically effective at relatively high doses. High antibody concentrations, such as to minimize dose volumes and to make administration more patient-friendly (e.g. subcutaneous injection instead of intravenous infusion, decreased number of injections) are therefore generally desirable in pharmaceutical formulations.
Aggregation, in effect, can lead to loss of active antibody therapeutic, leading to unreliable and ineffective dosing. More significantly, aggregates may also exhibit toxicity and trigger undesirable or serious immunogenic responses. Aggregation resulting in the precipitation of large particulates which impede flow is undesirable for any kind of parenteral application.
Antibody modification and degradation via chemical pathways such as oxidation, deamidation, isomerization, disulfide bond formation and other irreversible crosslinking reactions may also occur over time and lead to inactivation of the antibody, as well as trigger aggregation. These reactions, along with aggregation, are often accelerated at elevated temperatures; refrigeration is consequently almost always a prerequisite. In many of these chemical reactions, water also plays a significant role either as a mediator or as a reactive intermediate such as in the hydrolytic cleavage of amide bonds. The exclusion of water, such as by lyophilization, or freeze-drying, to form a solid-state powder formulation may thus be an effective measure towards preparing a stable formulation of an antibody therapeutic.
Some of the formulations of marketed therapeutic antibody or antibody derivatives/fragments are based on lyophilized powder formulations which need to be reconstituted under sterile conditions with aqueous media shortly prior to administration by a trained medical or paramedical practitioner. For example, omalizumab (e.g. Xolair®, marketed by Genentech) is available as a lyophilized powder in a single-use vial.
The reconstitution of the lyophilized antibody in sterile aqueous media as an extra step prior to actual administration, however, carries the risk of improper handling (e.g. shaking) or dosing, as well as contamination. The reconstitution step itself may trigger aggregation if the pH or temperature of the aqueous medium is suboptimal, the time allowed for rehydration is too short or the vial is too aggressively shaken during the dissolving step. The propensity for waste is also higher, as failure to properly dissolve the lyophilized antibody product within the recommended time period usually requires for the sample to be discarded.
It should be noted that the lyophilization process step itself may induce aggregation and/or degradation. Additional stabilizing excipients such as saccharides or polyols are often added to the pre-lyophilization composition, along with other excipients such as bulking agents. The addition of other excipients may also be required after lyophilization in order to support the longer shelf-life of the antibody, adding to the number of components in the final formulation.
Ready-to-use liquid formulations would generally be preferred by the users, due to the ease of preparation for administration. If stable, a liquid formulation is also attractive for the pharmaceutical manufacturer due to the avoidance of lyophilisation, which is time-consuming and costly both during drug development and routine manufacture. Indeed, many marketed formulations of antibodies or antibody derivatives are aqueous-based solutions. With aqueous formulations, the pH of the medium can have a significant impact on the stability of the antibody in terms of promoting or reducing the likelihood of various degradative chemical reactions. Consequently, an optimized buffering system is always required, along with other formulation excipients such as antioxidant free-radical scavengers, surfactants and other anti-aggregation additives, or preservatives in order to provide stabilization to the antibody and counteract the various possible degradation processes that may occur during storage in an aqueous environment over time.
Alternative formulation options to lyophilization and aqueous solutions are also known, such as the use of non-aqueous liquids as carrier vehicles. For example, WO2012/121754 describes non-aqueous, high concentration suspension formulations comprising a hydrophobic vehicle such as sesame oil, and a viscosity-reducing agent such as ethyl oleate, and an anti-TNFα antibody. These compositions require addition of a viscosity-reducing agent that is fully miscible in the carrier, in order to make the oil carriers more amenable towards injection. Generally, the parenteral use of lipids and oils can cause pain and other undesirable side effects at the injection site. These types of compounds may also slow down the release of therapeutic agent, and are not ideal if rapid or immediate bioavailable is preferred.
Perfluorinated compounds have also been described as possible non-aqueous liquid carriers of biologically active agents such as proteins and peptides. For example, U.S. Pat. No. 6,458,376 describes compositions proposed for ophthalmic applications (such as topically applied eye drops) in which therapeutic/diagnostic compounds, including oligopeptides and protein growth factors are suspended in perfluorocarbons or fluorinated silicone oils and in the presence of at least one surfactant. There is no mention, however, of such compositions comprising antibodies or antibody fragments and derivatives.
U.S. Pat. No. 6,730,328 describes thermally stable formulations in which non-aqueous, hydrophobic, non-reactive vehicles such as mineral oil, perfluorodecalin, methoxyflurane, perfluorotributylamine and tetradecane are used for suspension compositions comprising proteins, proteinaceous compounds and nucleic acids. The formulations are proposed for parenteral, transdermal, mucosal, oral and enteral methods of administration, as well as their use for long-term continuous administration and delivery via an implantable device. However, no specific example of a suspension of an antibody or antibody fragment or derivative in such vehicles is disclosed, nor is there any teaching with regard to the stability of such compositions at elevated temperatures beyond a three month time point. The actual tissue compatibility of these types of compositions has not been demonstrated either.
WO 2011/073134 discloses solutions of ciclosporin, a cyclic polypeptide with a molecular weight of 1202.31 in a semifluorinated alkane, optionally in the presence of a cosolvent such as ethanol. Whilst suspensions and emulsions are mentioned as optional alternatives, there is no specific disclosure of such type of composition, or any composition comprising high molecular weight proteinaceous species in the kiloDalton range such as antibodies or antibody fragments or derivatives.
It is therefore an object of the present invention to introduce novel antibody compositions which overcome any of the limitations and disadvantages associated with formulations currently known in the art.